This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Diffusion weighted image (DWI) and perfusion-weighted image (PWI) have shown unique ability to assess the development of acute stroke. The perfusion-diffusion mismatch, derived from DWI and PWI, approximates the ischemia penumbra and has been used as the surrogate marker to detect the stroke lesion changes and evaluate the treatment efficacy. Because of the poor spatial resolution and accuracy of the perfusion-diffusion mismatch currently used in clinic, the fine structure of the lesion area cannot be defined. The novel parallel imaging and the continuous Arterial Spin Labeling(CASL) MRI techniques can be used to obtain high-resolution DWI and PWI images of the cortical and subcortical brain tissues. Nonhuman primate (NHP) stroke models are ideal for stroke research. A monkey ischemic stroke model with the intravascular occlusion by novel interventional approach has been developed at the Yerkes research center. The general aims of this project are 1) to develop and implement the novel MRI techniques to characterize the brain tissues after stroke onset with the high-resolution, quantitative MRI measurements on a high field (3T) clinical scanner, and 2) to evaluate the fate of tissue at risk during the tPA treatment on the monkey stroke model. The high-resolution DWI and PWI measurements for assessing the stroke lesion on a monkey stroke model have been developed during this reporting period.